A New Zero-suppressed Ternary Decision Diagram Algorithm

Jung, Woo Sik

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https://hdl.handle.net/2142/121844 Copy

Description

Title

A New Zero-suppressed Ternary Decision Diagram Algorithm

Author(s)

Jung, Woo Sik

Issue Date

2023

Keyword(s)

• Zero-suppressed ternary decision diagram
• Minimal cut sets
• Prime implicants

Abstract

Probabilistic safety assessment (PSA) plays a critical role in ensuring the safe operation of nuclear power plants. In PSA, event trees are developed to identify accident sequences that can lead to core damage, which are then converted into a core-damage fault tree. The accident sequences in a core- damage fault tree are represented by usual and complemented logical gates that represent failed and successful operation of safety systems, respectively. Minimal cut sets (MCSs) are calculated from the core-damage fault trees to determine the core damage frequency (CDF). The delete-term approximation (DTA) has been commonly used to approximately solve MCSs that represent accident sequence logics from core-damage fault trees. However, it is well known that this method results in an overestimation of the CDF when fault trees have many non-rare events. To address this issue, this paper introduces a new zero-suppressed ternary decision diagram (ZTDD) algorithm that avoids the overestimation of CDF. The ZTDD algorithm can optionally calculate MCSs or prime implicants from the core-damage fault tree. When prime implicants are calculated from the core-damage fault tree with non-rare events using the ZTDD algorithm, the accurate CDF can be calculated from the prime implicants. This paper describes the new ZTDD algorithm in detail, including the ZDD structure, formula of the ZTDD algorithm, minimization, probability calculation, and an example. The ZTDD algorithm is a powerful tool that can accurately calculate the CDF and improve the safety of nuclear power plants.

Type of Resource

text

Language

eng

Handle URL

https://hdl.handle.net/2142/121844

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